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The second observation I would like to make concerns the balance of the space program. After Apollo and with the growth of ecological anxieties there has been a considerable buildup in the earth oriented aspects of the space program. These are fine, but should not be allowed to overshadow the outward directed programs, just because their value is easier to explain (or to exaggerate) to the layman.
In my lifetime, in fact in the last three decades, astronomy has revived from an almost "dead" science to one of the most exciting and alive sciences that flourish today. Radioastronomy, infrared, X-ray astronomy and planetary exploration have brought about this renaissance and have altered drastically our picture of the universe. NASA, by allowing observation from space, has played a vital role in advancing astronomical and astrophysical knowledge. This role must go on and should be augmented. Thus I would argue for the launching of space telescopes of increased capability, working at a variety of wavelengths, and designed for particular kinds of research. These are most certainly needed and are appropriate shuttle missions. I would also argue for the continuation of the planetary system exploration until the major remaining questions have been answered. We will get more information per dollar in this program from widely different missions than by repeating, or nearly repeating missions. Viking II added little to the information obtained by Viking I.
After Pluto, What?
If the planetary missions are continued at the rate of one or two per year, the day is not far off when diminishing return will set in. Once we have probed Jupiter, orbited Saturn and examined Titan, once we have flown past Uranus, Neptune and possibly Pluto, what fundamentally new missions remain? We will have explored the sun's
family of planets and will find ourselves on the brink of REAL space interstellar space a space so vast that our present rockets would require about 40, 000 years to reach the nearest star. Nuclear rockets could get there in a decade by squandering a substantial fraction of the earth's nuclear energy resources. Interstellar travel is either politically or economically impossible with any technology we can foresee.
In all probability there is no other life in the solar system besides that on earth. Certainly there is no advanced life. Yet the burst of progress that has occurred over the last two decades in astronomy, astrophysics, magnetohydrodynamics, planetary science, and biochemistry has led to the conviction among most scientists that habitable planets are common in the universe that there are perhaps 10 billion such in our Milky Way galaxy alone habitable planets life is almost certain to start and to evolve. We see the sun as a common middle-class star, earth as a common kind of planet.
and that on
Thus today we contemplate a universe teeming with life, much of it intelligent, that the universe has evolved in the 15 billion years since it all began. To many scientists it seems incredible that these billions of oases of life will flower and die never having contacted one another; in fact, it seems likely that communication among them is presently going on and has been for billions of years. The accumulated knowledge of a galactic community of such a size and age staggers the mind. We can only guess at the direction its science and art have taken. Yet if other civilizations have come into contact, can anything less be our destiny? How can we remain galactic recluses, forever ignorant of the mainstream of life?
Communication between civilizations separated by thousands of light years is possible with equipment no more powerful than that we already have. The Arecibo Observatory could communicate with its twin clear across the Galaxy. Beacons intended for our detection could be found with existing radio telescopes. But out of the millions of distinct directions such telescopes can be pointed only a few would contain signals. And out of the literally billions of channels to which their receivers can be tuned only a few would contain anything but natural background noise. The reason that we have not already detected extraterrestrial intelligent signals is that we have not pointed our telescopes in the right directions at the right times with their receivers tuned to the right frequencies. Also, existing telescopes may not be large enough.
We can expect signals of two general types: signals radiated by the other civilization for its own use, or beacons intended for our detection. Either type of signal might be beamed or broadcast. Beaming a signal can increase its intensity a million-fold and thus require one millionth the transmitter power per beam, but it also requires thousands of beams if all the good suns within, say, 100 light years are to be covered continuously by the sending civilization.
Existing radio telescopes could detect beamed beacons out to thousands of light years, but beyond 100 or 200 light years it is doubtful if beacons will be beamed. Thus a targetted search of the thousand or more good suns within 100 light years would detect any near neighbors who might be calling us. To detect unintended signals to eavesdrop on their UHF-TV or to detect a distant omnidirectional beacon requires an antenna system larger than we now have. The
Cyclops study (1971) proposed a targetted search initially with a small system and then repeated and carried to more distant stars as the antenna array was increased in size. In this way weaker and weaker signals from weaker or more distant sources would become detectable, and no larger a system would be built than needed to detect the strongest signal.
In the years since Cyclops, NASA/Ames Research Center has sponsored a SETI Science Workshop. The introduction and summary conclusions of this Workshop are included here as Appendix A. The report endorses the targetted search strategy as the conventional wisdom of SETI, but suggests in addition an all-sky survey for powerful signals that might come from unexpected directions.
The Jet Propulsion Laboratory has proposed an all-sky, wide frequency band search using very modest sized antennas, while the Ames Research Center proposed a targetted search with a much narrower channel spectrum analyzer covering a preferred frequency band (the "water hole"). The sky survey would cost about $14 million and the targetted search $7 million over a five year period. Because of the reduced time per direction and the wide bandwidths, the JPL all-sky survey is between a thousand and a million times less sensitive than the Ames targetted search; it is so insensitive that a beacon 100 light years away would not be detected unless it were beaming 100 million watts at us or else broadcasting about 100 times the total electrical power generated on earth! In view of these numbers the all-sky survey is unlikely to succeed as SETI. Yet the early indications are that of the two programs this is the only one NASA has seriously sought to fund for FY'79. If the less expensive Ames program is not
funded for FY'79, the group there that has kept SETI alive for seven 录
Project Cyclops, NASA document CR114445
years may be forced to disband, and this would, in my opinion, be a sad loss. Our microwave window on space is rapidly filling with other services. Unless an active program is underway by 1979 it may be impossible to protect key frequency bands such as the "water hole".
SETI is a gamble. One cannot guarantee success. But the stakes are so high that even a substantial effort seems justified. If this Committee feels that a few million dollars per year is not too much to spend on an effort to detect other intelligent life, and ultimately perhaps to link mankind with that life and its cosmic purposes, you should say so now loudly and clearly. NASA is not pursuing SETI as fully and effectively as it would if Congressional support were evident. The technology is there and waiting. Only your encouragement is needed.
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